Gas burners



1970 V F. cs. ROPER I 3,

GAS BURNERS Filed Sept. 9, 1968 2 Sheets-Sheet 1 I nventor F- G. RoPER y im Dec. 1, 197 0 F. G. ROPER 4,

GAS BURNERS Filed Sept. 9, 1968 v 2 Sheets-Sheet 2 /8 lnvenlor F. G. ROPCR United States Patent Oifice 3,544,255 Patented Dec. 1, 1970 3,544,255 GAS BURNERS Francis George Roper, London, England, assignor to The Gas Council, London, England, a British body corporate Filed Sept. 9, 1968, Ser. No. 758,344

Claims priority, application Great Britain, Sept. 29, 1967,

Int. Cl. F23d 13/24 US. Cl. 431-350 6 Claims ABSTRACT OF THE DISCLOSURE A gas burner of the neat gas type which is intended for burning natural gas or other gas containing a predominant proportion of methane or other hydrocarbon gas, comprises a nozzle and a bluff body stabiliser which is fixed to the nozzle and extends into the stream of gas which, in use, issues from the nozzle. The blufi body stabiliser is fixed to the burner in a position which is so close to the nozzle orifice that, with gas issuing from the nozzle at a discharge pressure which would be suflicient to cause the flame to lift away from the nozzle in the absence of the stabiliser, the gas impinges on the stabiliser while its flow is still streamlined. The part of the surface of the stabiliser closest to the nozzle is adjusted in position, within the limits set by the requirement that the gas impinges on the stabiliser while its flow is still streamlined, so that the noise produced by the burner when in operation is minimised.

This invention relates to gas burners, which are primarily intended for domestic purposes, of the neat gas, or nonaerated jet, type in which the gas to be burned emerges from a nozzle without any premixture with air. The advantages of this type of burner are well known and amongst the main ones is that they avoid the need for internal air passages which can collect dust and also form a source of flame noise.

However, if attempts are made to burn natural gas or other gas containing a predominant proportion of methane or other hydrocarbon gases in conventional burners of the neat gas type, the flame tends to blow ofI from the burner and be extinguished. If the gas input pressure is reduced to avoid this, the flame tends to soot due to poor entrainment of air. The aim of this invention is to provide a neat gas burner which overcomes these difiiculties and achieves aeration of the flame without undue noise.

According to this invention, such a gas burner comprises a nozzle and a bluff body stabiliser which is fixed in a position such that, in use, with gas issuing from the nozzle at a discharge pressure which would be sufficient to cause the flame to lift away from the nozzle in the absence of the stabiliser, the gas impinges on the stabiliser whilst its flow is still streamlined, the surface of the stabiliser closest to the nozzle being spaced from the nozzle orifice by a distance which is set to minimise the noise produced by the burner when in operation.

If the stabiliser alone is provided to stabilise the flame, the distance of the closest part of its surface from the nozzle orifice is preferably from 1 to 3 mm. However, by providing a shield which extends at least partly around the gas jet between the nozzle orifice and the stabiliser, the preferred distance of the stabiliser from the orifice is increased to from 4 to 6.5 mm.

It has been discovered that the provision of a bluff body stabiliser at a distance from the nozzle orifice within the limits set out, very considerable advantages are obtained when natural gas or other predominantly hydrocarbon gas is burnt at the burner. First of all, the flame front is stabilised and vortices of air which cause uneven combustion and hence small explosions which produce noisy operation are avoided. The flame produced is nonlambent and not excessively luminous or sooty which indicates that the air entrainment is satisfactory, and the flame is highly resistant to blow off. The gas flow is forced to diverge when it impinges on the stabiliser and this divergence can be used to improve the air entrainment. The flame shape can be controlled by adjusting the shape of the bluff body stabiliser.

The blufl" body stabiliser may be of various shapes, but a rod of circular cross section is simple and produces satisfactory results. When the rod is circular, its diameter is not critical but between 3 mm. and 5 mm. has been found satisfactory with a burner having a nozzle diameter of 0.5 mm. or with a nozzle of the well-known slotted port type giving a fan-shaped flame, for example a Bray 118 size T jet. The stabiliser may be made of ceramic material or quartz, but any smooth heat-resistant material is satisfactory.

With a nozzle of the slotted port type, for example a Bray 118 size T jet, particularly satisfactory results are achieved when, in addition to a bluff body stabiliser in the form of a circular rod extending centrally across the burner at right angles to the plane of the flame produced by the nozzle, a shield is provided extending around the ends of the flattened stream of gas issuing from the burner nozzle, between the nozzle and the stabiliser. The shield may be in the form of an elongated trough with the centre portions of its side walls, adjacent the ends of the stabiliser cut way. The trough extends in the direction in which the flame is elongated and air is drawn into the flame through the cutaway sides of the trough where the flame extends around the stabiliser thus reducing spluttering on light-up. Preferably, the trough has its end walls inclined to the axis of the nozzle, that is to the vertical when the burner is set with the nozzle discharging directly upwards as is usual. The angle of inclination of the ends of the trough is preferably substantially 20 to the axis of the nozzle.

The base of the trough is preferably at substantially the same height as, or slightly above, the nozzle orifice and outwardly projecting flanges are preferably provided at the edges of the end walls. The gas flowing from the burner nozzle flows upwards over the end walls of the trough and outwards to some extent over the flanges which assist in anchoring the flame and preventing lift at its edges.

Two examples of burners constructed in accordance with the invention are illustrated in the accompanying drawings in which:

FIG. 1 is a side view partly in section of one example;

FIG. 2 is a similar view of the second example; and,

FIG. 3 is a plan of the example shown in FIG. 2.

In the example shown in FIG. 1, the burner comprises a body 1 having a screw-threaded tubular shank 2 for screwing into a tapped hole in the gas supply pipe and a head 3 with a central gas outlet nozzle having an orifice 0.65 mm. in diameter. A collar 4, which is shown in section, fits around the head 3 and rests on the body 1. Two strips 5, one of which is shown in FIG. =1, are welded at diametrically opposite positions to the collar 4 and project upwards and then inwards. The tips of the inwardly bent ends of the strips 5 are fixed to and support a V-shaped rod 6 which is 4 mm. in diameter. In this example the rod 6, which forms a buff body stabiliser is made of stainless steel, quartz, or ceramic material. The lowermost part of the apex of the rod 6 is spaced between 1 and 2 mm. above the orifice of the nozzle in the head 3. A second rod 6a of similar material is fixed at right angles to the rod 6 by strips 5a. The centre of the rod 6a, which is straight is fixed in a position at which the centre of a flame produced by the burner would stabilise in the absence of the rod 6a.

With methane supplied to the nozzle at a pressure of up to inches water gauge a flame stabilises on the rods 6 and 6a with an outline of the form indicated in chaindotted lines at 7. The flame stabilises as shown in a position in which it is lifted from the nozzle in the head 3. The flame burns quietly and in a stable manner.

In the second example shown in FIG. 2 and 3 of the drawings, the burner again has a body 1 with a shank 2, but a head 8 has a nozzle 9 of the slotted port type formed in it. The nozzle 9 has a slot-like orifice producing a fan-shaped flame parallel to the plane of the drawing and in this example the burner nozzle is a Bray 118 size T jet. 7

A collar 10 fits around the head 8 and rests on the body 1. The collar 10 has a shield 11 formed integrally with it. The shield 11 has an elongated trough shape with a bottom 12, side walls 13 and end walls 14. The end walls 14 are inclined to the vertical, that is to the axis of the nozzle orifice 9 at an" angle of 20. This angle of inclination is not absolutely critical, but some inclination of about this magnitude greatly improves the performance of the burner. Horizontal flanges 15 project outwards from the edges of the end walls 14.

The central portions of the side walls 13 are cut away to form an opening 16 at each side of the shield 11. These openings allow air to be drawn in to the stream of gas issuingfrom the orifice 9 by a venturi effect. A blufi body in the form of a stainless steel rod or tube 17 of low thermal mass extends centrally across the shield 11 intersecting the axis of the nozzle orifice 9 at right angles. The rod 17 is held in position by support bars 18 fixed to the side walls 13 and in this example has the lowermost part ofits periphery spaced 5.5 mm. above the nozzle orifice 9. The nozzle orifice 9 itself is spaced slightly below the upper surface of the bottom 12 and the lowermost part of the rod 17 is spaced 4.3 mm. above the upper surface of the bottom 12.

When-methane at a pressure of 5 inches water gauge is supplied to the burner and is ignited, a quiet, stiff flame with a small amount of yellow tipping is produced and has approximately the outline indicated in chain-dotted lines at 19 in FIG. 2. In this example, owing to the presence of the shield 11, the flame 19 is stabilised on the burner head 8 rather than on the bluif body stabiliser as is the case in the first example shown in FIG. 1. The edges of the flame 19 are anchored on the flanges 15 which are important for this purpose. A heat input of approximately 2800 B.t.u. per hour is produced. 1

A great advantage of the example of the burner illustrated in FIGS. 2 and 3 of the drawings is that a standard slotted port burner can be converted into the burner shown by the addition of the shield 11 with the bluff body stabiliser rod 17 fixed to it as a separate assembly and for fitting all thatis necessary to push thecollar 10 over the burner head 8 and to set the longitudinal axis of the shield 11 parallel to the plane of the fan-shaped flame produced by the burner.

What is claimed is:

1. A gas burner of the neat gas-type comprising a nozzle of the slotted port type including means defining a nozzle orifice, a bluff body stabilizer in the form of a circular rod, means fixing said bluff body stabilizer to said nozzle adjacent said orifice in a positionin which it extends centrally across said burner atright angles to the plane of the flame producedby said slotted port nozzle so that thesurface of saidbluif-body stabilizer closest to the nozzle is spaced a distance of from 4 to 6.5 mm. from the orifice, a shield, and means fixing said shield to said burner with said shield extending around the ends of a flatterned stream of gas which, in use, issues from said slotted port, and at least partly around said burner between said orifice and said blufi body stabilizer.

2. A burner as claimed in claim 1, wherein said shield is in the form of an elongated trough including a bottom wall and side walls and-end walls extending from said bottom, centre portions of said side walls, adjacent the ends of said blufl body stabilizer being cut away and said trough extending in the direction of said plane of said flame.

3. A burner as claimed in claim 2, wherein said end walls extend from said bottom with an inclination outwards to the axis of said nozzle.

4. A burner as claimed in claim 3, wherein said inclination of said end walls is-at an'angle of substantially 20 to said axis of said nozzle. V

'5. A burner as claimed in claim 3, further comprising flanges projecting outwards from the tops of said end walls.

6. A burner as claimed in claim 3, wherein said bottom wall' of said trough is slightly above said nozzle orifice.

References Cited UNITED STATES PATENTS 3,238,994 3/1966 Kirk 431-350 FOREIGN PATENTS 2,119 1858 Great Britain 239-518 2,265 1880 Great Britain 239-518 1,144,041 1959 Germany 239 s1s CARROLL B. DORITY, IR. Primary Examiner U.S. c1. X.R. 431-341 

